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Swainson's Hawk - Buteo swainsoni

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Global Rank: G5
State Rank: S4B
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM: SENSITIVE
FWP Conservation Tier: 2
PIF: 3


 

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Copyright by Borror Laboratory of Bioacoustics, Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, OH, all rights reserved.
State Rank Reason (see State Rank above)
While there is concern about the status of some local populations, statewide populations have increased in recent years.
  • Details on Status Ranking and Review
    Swainson's Hawk (Buteo swainsoni) Conservation Status Review
    Review Date = 12/22/2011
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)

    Comment380531 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide

    Long-term Trend

    ScoreD - Moderate Decline (decline of 25-50%)

    CommentSpecies was heavily persecuted by early settlers who considered it a threat to domestic foul and sheep. Pesticide application in both breeding and wintering range has also been identified as a cause for declines in last half century.

    Short-term Trend

    ScoreF - Increasing. Increase of >10% in population, range, area occupied, and/or number or condition of occurrences

    CommentBBS data is of moderate credibility in Montana and shows a significant increase of 2.4% per year or + 27% increase per decade. BBS for surrounding states and provinces mostly show increasing trends. Raptor survey route data in Montana for the past 35 years shows mostly stable, but sometimes widely varying, numbers. Over the last 10 years, raptor survey route data shows a steady and seemingly clearly increasing trend.

    Threats

    ScoreF - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.

    CommentHabitat loss, pesticides on summer and winter ranges and vehicle collisions are probably the greatest threats.

    SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.

    CommentProbably respond relatively quickly to habitat and prey base changes.

    ScopeModerate - 20-60% of total population or area affected

    CommentGrassland/shrubland habitats being widely (20-605) affected.

    ImmediacyModerate - Threat is likely to be operational within 2-5 years.

    CommentOngoing

    Intrinsic Vulnerability

    ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).

    Comment

    Environmental Specificity

    ScoreC - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.

    CommentForage over a large variety of habitats and nest sites aren't that limited.

 
General Description
Adults are dark brown above, and white with chestnut-brown bib below; tail grayish-brown, finely barred, becoming lighter toward the base. In flight, the wing undersides appear two-toned, with the flight feathers dark and the leading edge of the wing white. The wings of Swainson's Hawks are slightly more pointed than those of other buteos. Dark-phase Swainson's Hawks appear all dark brown above and below and on the entire wing undersides, making them look like a miniature eagle. Intermediate color phases occur, with dark brown bibs and chestnut barring on the belly. Immatures lack the bib and are more strongly barred or streaked underneath. Swainson's Hawks range in length from 18 to 22 inches, and have a wingspan of 48 to 52 inches.

Diagnostic Characteristics
All other buteo hawks have white flight feathers. Also, Swainson's Hawks have longer, narrower wings than other buteos. Red-tailed Hawks are slightly larger, have a dark belly band and no bib, while Swainson's Hawks have a bib, but no belly band.

General Distribution
Montana Range



Western Hemisphere Range


eBird Occurrence Map
 


Summary of Observations Submitted for Montana
Number of Observations: 2118

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

Breeding
(direct evidence "B")


Breeding
(indirect evidence "b")


No evidence of Breeding
(transient "t")


Overwintering
(regular observations "W")


Overwintering
(at least one obs. "w")



 

(Records associated with a range of dates are excluded from time charts)



Migration
Swainson's Hawks leave in late September, migrating to Argentina for the winter. They often migrate in large flocks. Bozeman migration: April 25 to May 15 and September 2 to Septmeber 10; no detectable peaks (west of main migration path). Migration late April and early September (Davis 1961).

Habitat
Swainson's Hawks nest in river bottom forests, brushy coulees, and shelterbelts. They hunt in grasslands and agricultural land, especially along river bottoms. In Bozeman area, the birds inhabit the drier, open parts of the Gallatin valley (Skaar 1969).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Swainson's Hawks prey on a wide variety of small mammals, songbirds and insects.

Ecology
Formerly rare in the Fortine area, but not seen in summer for 30 years. Has apparently decreased in numbers in the Bozeman area in the last century (Skaar 1969).

Reproductive Characteristics
Flimsy nests are built in trees and shrubs, often as low as four feet from the ground. Swainson's Hawks are more tolerant of humans than other hawks, and will often nest close to occupied houses. One to three eggs are laid in May, and incubated for about 28 days. The young fledge in late July and August. Nests with eggs range from early May to mid-July, but June is the common nesting month (Davis 1961).

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • Allen, G. T. 1979. An assessment of potential conflicts between nesting raptors and human activities in the Long Pines area of southeastern Montana with special emphasis on uranium development. M.S. thesis, Washington State University, Pullman. 109 pp.
    • American Ornithologists' Union. 1998. Check-list of North American birds. 7th edition. American Ornithologists' Union, Washington, D.C. 829 pp.
    • Becker, Dale M., 1980, A Survey of raptors on national forest land in Carter County, Montana. Final Progress Report: 1977-1979.
    • Cameron, E. S. 1891. Letter in regard to migration of Swainson's hawks in Montana. Ibis, 6th series, 111:623-625.
    • Cameron, E. S. 1908. Changes of plumage in Buteo swainsoni. Auk 25:468-471.
    • Cameron, E. S. 1913. Notes on Swainson's Hawk {Buteo swainsoni) in Montana. Auk 30:167-176.
    • Cameron, E. S. 1913. Notes on the Swainson's hawk ... in Montana. Auk 30: 167-176.
    • Cameron, E.S., 1908, Changes of plumage in Buteo swainsoni. Reprint from The Auk, Vol. XXV, No.4, October, 1908.
    • Cameron, E.S., 1913, Notes on Swainson's hawk (Buteo swainsoni) in Montana. Reprint from The Auk, Vol. XXX, No. 2, 1913.
    • Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp.
    • Dechant, J. A., M. F. Dinkins, D. H. Johnson, L. D. Igl, C. M. Goldade, and B. R. Euliss. 2003a. Effects of management practices on grassland birds: Swainson’s Hawk. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center
    • Dobkin, D. S. 1992. Neotropical migrant landbirds in the Northern Rockies and Great Plains. U.S.D.A. For. Serv. N. Region Publ. R1-93-34. Missoula, Mont.
    • Dunkle, S. W. 1977. Swainson's hawks on the Laramie Plains, Wyoming. Auk 94:65-71.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1976, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1976. Proj. 135-85-A. December 31, 1976.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1977, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1977. Proj. 164-85-A. December 31, 1977.
    • Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster Inc. New York. 785 pp.
    • Elliott, Joe C. and Hydrometrics, Inc., Helena, MT., 1994, Supplement to wildlife baseline investigation life-of-mine expansion plan: Regal Mine, Barretts Minerals, Inc., Madison County, Montana. August 2000. In Life-of Mine Expansion Plan: Barretts Minerals, Inc., Regal Mine, Madison County, Montana. Vol. 2. App. C: Baseline Wildlife Reconnaissance. December 1999.
    • England, A. Sidney, Marc J. Bechard, and C. Stuart Houston. 1997. Swainson's Hawk (Buteo swainsoni). Species Account Number 265. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online database
    • England, A.S., M.J. Bechard and C.S. Houston. 1997. Swainson's Hawk, in Birds of North America, No. 265. A. Poole and F. Gill, eds. The Academy of Natural Sciences, Philadelphia and The American Ornithologist's Union, Washington, D. C.
    • Gilmer, D. S., and R. E. Stewart. 1984. Swainson's hawk nesting ecology in North Dakota. Condor 86:12-18.
    • Gniadek, Steve. 1983. Southwest Glendive Wildlife Baseline Inventory. BLM, Miles City District. 56pp with appendices.
    • Graham, Dean, and Craig Swick., 1977, A Field evaluation of the cyclone seeder for reducing Richardson ground squirrel populations causing damage in central Montana . August 1977.
    • Green, G. A. and M. L. Morrison. 1983. Nest-site characteristics of sympatric ferruginous and Swainson's hawks. Murrelet 64:20-22.
    • Hansen, R. W. 1995. Ecological relationships between nesting Swainson's and red-tailed hawks in southeastern Idaho. J. Raptor Res. 29:166-171.
    • Hendricks, P., and K. H. Dueholm. 1995. Cliff-nesting raptor survey of the Sioux District, Custer National Forest: 1994. Unpubl. report to U.S.D.A. For. Serv., Custer N.F., Billings. 20 pp.
    • Johnsgard, P. A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp.
    • Land & Water Consulting, Inc., Missoula, MT., 2002, Montana Dept. of Transportation Wetland Mitigation Monitoring Report, Year 2001: Beaverhead Gateway, Dillon, Montana. Proj. No. 130091.011. July 2002. In 2001 Wetland Mitigation Monitoring Reports, Vol. I.
    • Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana Bird Distribution, 6th Edition. Montana Audubon: Helena, MT, 144 pp.
    • Lockhart, J. Michael, 1976, Effects of coal extraction and related development on wildlife populations. Annual progress report; Calendar year 1976. In Decker Coal Company West Pit Permit. Vol. 3. 26.4.304(10-11), 305, 306, and 307. Updated Rules Rewrite, July 1, 1991. Appendix F.
    • Lockhart, J. Michael, and Terrence P. McEneaney, 1978, Effects of coal extraction and related development on wildlife populations. Annual progress report; Calendar year 1978. In Decker Coal Company West Pit Permit. Vol. 3. 26.4.304(10-11), 305, 306, and 307. Updated Rules Rewrite, July 1, 1991. Appendix F.
    • Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
    • Schmutz, J. K. 1984. Ferruginous and Swainson's hawk abundance and distribution in relation to land use in southeastern Alberta. Journal of Wildlife Management 48:1180-1187.
    • Schmutz, J. K. 1984. Ferruginous hawk and Swainson's hawk abundance and distribution in relation to land use in southeastern Alberta. J. Wildl. Manage. 40:438-440.
    • Schmutz, J. K. 1987. The effect ofagriculture on Ferruginous and Swainson's Hawks. J. Range Manage. 40:438-440.
    • Schmutz, J. K. and D. J. Hungle. 1989. Populations of ferruginous and Swainson's hawks increase in synchrony with ground squirrels. Can. J. Zool. 67:2596-2601.
    • Schuntz, J. K., R. W. Fyfe, D. A. Moore and A. R. Smith. 1984. Artificial nests for ferruginous and Swainson's hawks. Journal of Wildlife Management 48(3):1009-1013.
    • Sexton, O.J. and K.R. Marion. 1974. Probable predation by Swainson’s hawks on swimming spadefoot toads. Wilson Bulletin 86(2): 167-168.
    • Stewart, R.E. 1975. Breeding birds of North Dakota. Tri-College Center for Environmental Studies, Fargo, North Dakota. 295 pp.
    • Thomas, J. W. (ed). 1979. Wildlife habitats in managed forests: the Blue Mountains of Oregon and Washington. Agriculture Handbook 553, USDA, Forest Service, Wildlife Management Institute, Washington, DC. 512 pp.
    • U.S. Forest Service. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. U.S. Department of Agriculture, Forest Service Agricultural Handbook 688. 625 pages.
    • Waage, Bruce C., compiler., 1985, Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1984 Field Season. October 1985.
    • Waage, Bruce C., compiler., 1986, Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1985 Field Season. December 1986.
    • Western Energy Co., Colstrip, MT. Unpub., 1983, Western Energy Company's Application for Amendment to Surface Mining Permit NO. 8003, Area B: sections 7, 8, 17,18 T1N R41E, sections 12, 13 T1N R40E, Mining Expansion. March 1983.
    • Western Energy Co., Colstrip, MT., 1981, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Report, 1981.
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Citation for data on this website:
Swainson's Hawk — Buteo swainsoni.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on July 31, 2014, from http://FieldGuide.mt.gov/detail_ABNKC19070.aspx
 
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